Browsing by Author "Wang, A."

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    Fiberoptic Temperature Sensors Based on Differential Spectral Transmittance Reflectivity And Multiplexed Sensing Systems
    Wang, A.; Wang, G. Z.; Murphy, Kent A.; Claus, Richard O. (Optical Society of America, 1995-07-01)
    A concept for optical temperature sensing based on the differential spectral reflectivity/transmittance from a multilayer dielectric edge filter is described and demonstrated. Two wavelengths, lambda(1) and lambda(2), from the spectrum of a broadband light source are selected so that they are located on the sloped and flat regions of the reflection or transmission spectrum of the filter, respectively. As temperature variations shift the reflection or transmission spectrum of the filter, they change the output power of the light at lambda(1), but the output power of the light at lambda(2) is insensitive to the shift and therefore to the temperature variation. The temperature information can be extracted from the ratio of the light powers at lambda(1) to the light at lambda(2). This ratio is immune to changes in the output power of the light source, fiber losses induced by microbending, and hence modal-power distribution fluctuations. The best resolution of 0.2 degrees C has been obtained over a range of 30-120 degrees C. Based on such a basic temperature-sensing concept, a wavelength-division-multiplexed, temperature-sensing system is constructed by cascading three sensing-edge filters that have different cutoff wavelengths along a multimode fiber. The signals from the three sensors are resolved by detecting the correspondent outputs at different wavelengths.
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    Investigation And Application Of The Frustrated-Total-Internal-Reflection Phenomenon in Optical Fibers
    Rahnavardy, K.; Arya, Vivek; Wang, A.; Weiss, J. M. (Optical Society of America, 1997-12-01)
    A detailed investigation of the frustrated-total-internal-reflection (FTIR) phenomenon in silica-glass-based optical fibers and its application to simple intensity-modulated strain and pressure sensors is presented. Such sensors may be readily fabricated with silica-based fibers and can be easily modified with sapphire fibers for high-temperature industrial applications where conventional silica-based fiber sensors are not feasible. We present the all-fiber FTIR sensor and show good correlation between theory and experiment. We also present results for the design and implementation of a prototype FTIR-based fiber pressure sensor. (C) 1997 Optical Society of America.
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    Relationship of physical activity and sleep quality to quality of life among cancer survivors: findings of the day and night study
    Rafie, Carlin; Ning, Y.; Wang, A.; Houlihan, R. (2016-11-15)
    Background: Diet and lifestyle may have a role in quality of life for cancer survivors. This study compared diet, physical activity and sleep quality between cancer survivors and controls, and the relationship to quality of life. Methods: Participants were recruited from southern Virginia. (1)Diet, physical activity, sleep quality (Pittsburgh Sleep Quality Index,psqi), and quality of life (QOL,SF-36) surveys were completed, (2)data on sleep/wake patterns and ambient light exposure was collected by an actigraphy-based data logger worn 7 days, (3)fasting blood and morning urine samples were collected for Vitamin D and urine melatonin analysis. Lower sleep quality scores indicate better sleep quality. Results: 131 cancer survivors and 41 controls participated in the study. Participants were majority female (89%), 24% black, with mean age of 59 years. Cancer sites included breast (68%), colon (8%), prostate (6%), lung (4%), and other (14%). Survivors had higher BMI compared to controls (29.6 vs 17.1 km/m2, ρ=0.036), and were more likely to be sedentary χ2[(2,N=172)11.11,ρ=0.004]. Calorie and macronutrient intake did not differ. Survivors had worse sleep quality than controls (psqi=6.6 vs 4.9,ρ=0.02) and lower physical (263.8 vs 323.5,ρ<0.0001) and mental QOL composite scores (295.4 vs 340.4,ρ=0.002). Sleep quality scores were inversely associated with mental and physical QOL (-0.48 & -0.43, ρ<0.0001). Physical activity was directly correlated with mental and physical QOL (R=0.21 & R=0.22,ρ=0.006). Melatonin was lower in survivors (32.4 vs. 52 ng/mg,ρ=0.002). Serum Vitamin D3 correlated with ambient light exposure (R=0.184,p=0.02) and outdoor physical activity (R=0.16,p=0.05). Conclusions: Cancer survivors were more sedentary, had poorer quality of sleep and quality of life than controls. Physical activity and sleep quality were associated with quality of life, which has implications for physical activity and sleep behavior recommendations for cancer survivors. Vitamin D3 is a potential biomarker of outdoor physical activity. Keywords: Physical activity, sleep quality, quality of life